During aging, or in certain pathological conditions, reduction of brain catecholamines causes the regulatory processes controlling pituitary hormone secretion to decay. Of concern in this invention are reciprocal changes in growth hormone (GH) which is reduced and prolactin which is increased. Catecholamines are somatotrophic because they provide primary stimuli to GHRH neurosecretory neurons which in turn stimulate the pituitary gland to release GH. In contrast, catecholamines directly suppress prolactin secretion by activating dopamine receptors on lactotrophs within the pituitary gland. Because of this dual action, age or pathology-related decreases in brain catecholamine concentrations or availability reduce GH secretion and increase prolactin secretion. Ultimately, lactotroph hypertrophy and/or hyperplasia lead to the development of prolactin secreting adenomas We have found that chronic stimulation of the somatotroph population by daily co-administration of a growth hormone releasing compound and GHRP-6 or analog thereof prevented lactotroph hypersecretion, proliferation and adenoma formation and caused regression of pre-existing tumors. Since prolactin secreting adenomas are treated clinically by surgery or by administration of dopamine agonists, our invention provides a new therapeutic alternative to the treatment of hyperprolactinemia and certain pathological changes in pituitary structure, i.e., the pharmacological stimulation of somatotrophs to reduce lactotroph hyperactivity and regression of lactotroph adenomas.